netdev - Re: [PATCH] cdc-ether: clean packet filter upon probe

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Date:	Thu, 14 Aug 2014 13:11:16 +0200
From:	Bjørn Mork <bjorn@...k.no>
To:	Oliver Neukum <oneukum@...e.de>
Cc:	davem@...emloft.net, netdev@...r.kernel.org
Subject: Re: [PATCH] cdc-ether: clean packet filter upon probe

Oliver Neukum <oneukum@...e.de> writes:

> There are devices that don't do reset all the way. So the packet filter should
> be set to a sane initial value. Failure to do so leads to intermittent failures
> of DHCP on some systems under some conditions.
>
> Signed-off-by: Oliver Neukum <oneukum@...e.de>
> ---
>  drivers/net/usb/cdc_ether.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/drivers/net/usb/cdc_ether.c b/drivers/net/usb/cdc_ether.c
> index 9ea4bfe..2a32d91 100644
> --- a/drivers/net/usb/cdc_ether.c
> +++ b/drivers/net/usb/cdc_ether.c
> @@ -341,6 +341,22 @@ next_desc:
>  		usb_driver_release_interface(driver, info->data);
>  		return -ENODEV;
>  	}
> +
> +	/* Some devices don't initialise properly. In particular
> +	 * the packet filter is not reset. There are devices that
> +	 * don't do reset all the way. So the packet filter should
> +	 * be set to a sane initial value.
> +	 */
> +	usb_control_msg(dev->udev,
> +			usb_sndctrlpipe(dev->udev, 0),
> +			USB_CDC_SET_ETHERNET_PACKET_FILTER,
> +			USB_TYPE_CLASS | USB_RECIP_INTERFACE,
> +			USB_CDC_PACKET_TYPE_ALL_MULTICAST | USB_CDC_PACKET_TYPE_DIRECTED | USB_CDC_PACKET_TYPE_BROADCAST,
> +			intf->cur_altsetting->desc.bInterfaceNumber,
> +			NULL,
> +			0,
> +			USB_CTRL_SET_TIMEOUT
> +		);
>  	return 0;
>  
>  bad_desc:

Hmm, the usbnet_generic_cdc_bind() function is used by the vendor
specific zaurus and rndis_host drivers as well.  Are we sure the
USB_CDC_SET_ETHERNET_PACKET_FILTER message is supported by all devices
supported by these drivers?


Bjørn
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